Lots of fossil fuel has been burned over two decades as government officials and sundry others have sped across the globe to frequent United Nations-sponsored meetings aimed at tackling catastrophic climate change.

Volcanoes spewing sun-reflecting particles into the atmosphere have partly offset the effects of man's carbon emissions over a 15-year period that has become a global-warming battleground, researchers say.

Tania Willis' letter ("Personal action now unavoidable to halt planet's destruction", June 1) quoted Al Gore and Jim Hansen in labelling carbon dioxide as the primary global warming pollutant. She has fallen short in showing why the 7.2 million people in Hong Kong must hold their breath because of the undesirable consequences claimed by her.

By the 2050s, more than 800,000 New York residents could be living in a flood zone that would cover a quarter of the city's land. Not only that, but New Yorkers could sweat out as many 32-Celsius days as is now normal for Alabama in the US' Deep South as effects of global warming take hold, a scientists' group convened by the city says.

On May 10, on his blog Al's Journal, former US vice-president Al Gore wrote, "Yesterday, for the first time in human history, concentrations of carbon dioxide, the primary global warming pollutant, hit 400 parts per million in our planet's atmosphere."